diff options
| author | Wolfram Sang <wsa@the-dreams.de> | 2018-01-03 22:50:51 +0100 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-01-03 22:50:51 +0100 |
| commit | fddfa22a4403cd19548de075ddada0c7c966a232 (patch) | |
| tree | f981a63ff0c1062aecb5ab48b0585ffe97a7c20b /include/linux/ptr_ring.h | |
| parent | 639136d2a70ab9837befb22ad5b3d67cb4db2216 (diff) | |
| parent | 0f30aca72c3b68f4b6a443193b574f14106cd61e (diff) | |
Merge tag 'at24-4.16-updates-for-wolfram' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux into i2c/for-4.16
"AT24 updates for 4.16 merge window
The driver has been converted to using regmap instead of raw i2c and
smbus calls which shrank the code significantly.
Device tree binding document has been cleaned up. Device tree support in
the driver has been improved and we now support all at24 models as well
as two new DT properties (no-read-rollover and wp-gpios).
We no longer user unreadable magic values for driver data as the way it
was implemented caused problems for some EEPROM models - we switched to
regular structs.
Aside from that, there's a bunch of coding style fixes and minor
improvements all over the place."
Diffstat (limited to 'include/linux/ptr_ring.h')
| -rw-r--r-- | include/linux/ptr_ring.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index 37b4bb2545b3..6866df4f31b5 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -101,12 +101,18 @@ static inline bool ptr_ring_full_bh(struct ptr_ring *r) /* Note: callers invoking this in a loop must use a compiler barrier, * for example cpu_relax(). Callers must hold producer_lock. + * Callers are responsible for making sure pointer that is being queued + * points to a valid data. */ static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr) { if (unlikely(!r->size) || r->queue[r->producer]) return -ENOSPC; + /* Make sure the pointer we are storing points to a valid data. */ + /* Pairs with smp_read_barrier_depends in __ptr_ring_consume. */ + smp_wmb(); + r->queue[r->producer++] = ptr; if (unlikely(r->producer >= r->size)) r->producer = 0; @@ -275,6 +281,9 @@ static inline void *__ptr_ring_consume(struct ptr_ring *r) if (ptr) __ptr_ring_discard_one(r); + /* Make sure anyone accessing data through the pointer is up to date. */ + /* Pairs with smp_wmb in __ptr_ring_produce. */ + smp_read_barrier_depends(); return ptr; } |